Integration Studio -> Visual Studio, data model mapping

I'm writing a tutorial for creating extensions for the company I work at, and I was looking at the way data models (so structures, entities, records and record lists) get mapped to Visual Studio classes. I know that they are prefixed by their OutSystems type (EN for Entities, RL for RecordLists, ST for structures and RC for records). If I have a Record instance, however, the Entity and the entity attributes get prefixed by ss (so, if I have a Post Record, I address the Entity by Post.ssENPost.ssTitle for example). I was wondering if there was any reason for the ss prefix that I haven't found?